1. Field of the Invention
The invention relates to a needle guard assembly for the needle part of a syringe body in the form of a needle guard that covers the needle and which is displaceable on the syringe body in the longitudinal direction, and with a grip plate being integrally formed on that end of the syringe body remote from the needle.
2. Description of the Related Art
Published European Patent Application EP 0 734 738 A2 discloses a safety syringe with a safety shield. In this known syringe, the safety shield is held securely in the retracted position by projections that issue from a collar. It is only when the safety shield is turned on the syringe barrel in such a way that the projections are flush with recesses in the collar, that the safety shield can be displaced toward the needle tip. In the safety position, the safety shield is held securely by locking teeth that engage with a locking wall of the collar.
The object of the invention is to construct a needle guard for the needle part of a syringe body, such that the protective safety cap can assume the functional position simply by displacing the piston rod, without additional measures.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a needle guard assembly. The needle guard assembly includes a syringe body ending with a needle. A piston rod in the syringe body has a receiving part and a push-in part that telescopes into the receiving part. A syringe-body grip plate is integrally formed on the syringe body. The syringe-body grip plate opposes the needle. A needle guard is arranged longitudinally along the syringe body and covers the needle when the needle guard is displaced longitudinally.
In accordance with another feature of the invention, the needle guard assembly further includes a catch mounting connecting the receiving part and the push-in part. The catch mounting can have a predetermined break point.
In accordance with another feature of the invention, the push-in part has a free end. A piston-rod grip plate connects to the free end.
In accordance with another feature of the invention, the syringe-body grip plate has an annular seat. The annular seat has an annular-seat diameter and the piston-rod grip plate has a piston-rod-grip-plate diameter. The annular-seat diameter can be greater than the piston-rod-grip-plate diameter.
In accordance with another feature of the invention, the annular seat can have an annular-seat end face. The piston-rod grip plate can lie flush with the annular-seat end face when the piston rod is in an inwardly telescoped state.
In accordance with another feature of the invention, the receiving part includes a longitudinally extending locking groove. The push-in part includes a longitudinally extending rib. The longitudinally extending rib matches the longitudinally extending locking groove. Alternatively, the receiving part includes a longitudinally extending rib and the push-in part includes a longitudinally extending locking groove; the longitudinally extending rib matches the longitudinally extending locking groove.
In accordance with another feature of the invention, the piston-rod grip plate includes a piston-rod-grip-plate inside and the needle guard includes a needle-guard end face. The piston-rod-grip-plate inside moves to abut the needle-guard end face.
In accordance with another feature of the invention, the needle guard includes a barb. The barb abuts the syringe-body grip plate when the needle guard is in a displaced position. The barb can attach circumferentially around the needle guard.
In accordance with another feature of the invention, the needle guard includes two opposing longitudinally extending recesses. The syringe-body grip plate can include two arc-shaped recesses. These areas complement the arc-shaped recesses.
The invention achieves this object by telescoping the piston rod parts into one another. The two parts of the piston connect to each other by a catch mounting. In one embodiment of the invention, the catch mounting has a predetermined break point. The push-in part of the piston rod can be provided at the free end with a piston rod grip plate. In a preferred embodiment, the grip plate of the syringe body has an annular seat which is perpendicular to the outside of the grip plate and whose diameter is greater than the diameter of the piston rod grip plate. In a preferred embodiment, the piston rod grip plate lies almost flush with the inner edge of the annular seat and flush with the end face of the annular seat of the grip plate of the syringe body when the piston rod is in the inwardly telescoped state.
The receiving part of the piston rod can be provided with at least one longitudinally extending locking groove. The push-in part of the piston rod can be provided with at least one longitudinally extending rib. The longitudinally extending ribs match the longitudinally extending locking grooves. According to the invention, the inside of the piston rod grip plate abuts the end face of the needle guard. A barb that is expediently arranged about the circumference at the outer end advantageously limits the displacement travel of the needle guard. The barb bears on the grip plate of the syringe body when the needle guard is in the displaced position.
In a further embodiment of the invention, the needle guard is guided securely on the syringe body. For this purpose, the grip plate of the syringe body has two arc-shaped recesses. The needle guard has two opposing longitudinally extending recesses. The needle guard is forcibly guided with the areas lying between the recesses in the arc-shaped recesses.
Other features that are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a needle guard for the needle part of a syringe body, it is nevertheless not intended to be limited to the details shown, because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.